/*
* Copyright (c) 2019, Nordic Semiconductor
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
*    list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this
*    list of conditions and the following disclaimer in the documentation and/or
*    other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its contributors may
*    be used to endorse or promote products derived from this software without
*    specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

import Foundation

public extension Data {
    
    /// Hex string to Data representation
    /// Inspired by https://stackoverflow.com/questions/26501276/converting-hex-string-to-nsdata-in-swift
    init?(hex: String) {
        guard hex.count % 2 == 0 else {
            return nil
        }
        let len = hex.count / 2
        var data = Data(capacity: len)
        
        for i in 0..<len {
            let j = hex.index(hex.startIndex, offsetBy: i * 2)
            let k = hex.index(j, offsetBy: 2)
            let bytes = hex[j..<k]
            if var num = UInt8(bytes, radix: 16) {
                data.append(&num, count: 1)
            } else {
                return nil
            }
        }
        self = data
    }
    
    /// Hexadecimal string representation of `Data` object.
    var hex: String {
        return map { String(format: "%02X", $0) }.joined()
    }
    
}
